Site-to-Site VPN with AWS

We have a requirement to setup a site-to-site VPN with a vendor who is using AWS cloud.

they generate one config file based on our FortiOS version and send us the file.

We are supposed to follow the config and setup the tunnel.

Questions, in the config file they ask us to configure WAN1 network interface and also enable BGP routing.

But WAN1 is current my WAN interface with my public ip address

How do i proceed from here ?

Go to Network Tab --> Interface -->

wan1 and edit vpn-0xxxxxxxx-0

vpn-0xxxxxxe0-0
a. IP : 169.254.xxx.xxx
b. Remote IP: 169.254.xxx.xxx/30
c. Select Ping
d. Administrative Status: Up
e. Select Ok.